1. Field of the Invention
The present invention relates to a device for controlling an engine equipped with a synchronous mesh-type automatic transmission mounted on an automobile. More particularly, the invention relates to a device for controlling an engine equipped with a synchronous mesh-type automatic transmission which decreases shock at the time of changing the speed, and improves the response and drive feeling at the time of changing the speed.
2. Prior Art
FIG. 5 is a diagram schematically illustrating the constitution of a general device for controlling an engine equipped with a synchronous mesh-type automatic transmission.
In FIG. 5, an engine 1 is equipped with an intake pipe la and an exhaust pipe 1b, and each cylinder in the engine 1 is provided with a fuel injection valve and an ignition means (not shown).
As is well known, further, the engine 1 is provided with a temperature sensor (not shown) for detecting the temperature of the cooling water, and a crank shaft of the engine is provided with a reference position sensor and a crank angle sensor (not shown) that works as a rotation sensor.
A throttle valve 2 is provided in the intake pipe 1a to set the amount of the air taken in by the engine 1, the throttle valve 2 being driven by a throttle actuator 3 having a motor.
The throttle valve 2 is further provided with a throttle opening sensor 4 for detecting the throttle opening degree xcex8.
An automatic transmission 5 having a clutch 5a and a transmission 5b is connected to the output side of the engine 1. Wheels (not shown) of the automobile are coupled to the engine 1 through the automatic transmission 5.
Shafts of the automatic transmission 5 are provided with an engine rotation sensor 6 that detects the input rotational speed as the engine rotational speed Ne and with a vehicle speed sensor 7 that detects the output rotational speed of the automatic transmission 5 as the output rotational speed.
An accelerator pedal and a gear shift lever operated by a driver are provided with an accelerator opening sensor 8 for detecting the accelerator opening degree xcex1 and with a shift position sensor 9 for detecting the shift position GS, respectively.
Detection signals (engine rotational speed Ne, throttle opening degree xcex8, etc.) of the sensors representing the operation conditions of the engine are input to a controller 10 constituted by an ECU (electronic control unit).
Based upon the input data representing the operation conditions, the controller 10 controls the fuel injection valve and ignition means in the engine 1, controls the throttle actuator 3, and controls the clutch 5a and transmission 5b in the automatic transmission 5.
The controller 10 includes an MPU 11 that constitutes a main body of the controller 10, a memory 12 that operates together with the MPU 11, an input port 13 for receiving data detected by various sensors, and an output port 14 for producing control signals.
The controller 10 controls the actuator that is related to the engine 1 based upon data representing the operation conditions and detected by the sensors.
That is, the controller 10 controls the fuel injection valve and ignition means in the engine 1 as well as the throttle actuator 3 that drives the throttle valve 2, and further controls the clutch 5a and the transmission 5b in the automatic transmission 5, so that the output torque of the engine 1 is transmitted to the wheels.
Further, in the device for controlling the engine equipped with a synchronous mesh-type automatic transmission as shown in FIG. 5, in general, the clutch 5a is disconnected at the time of changing the speed, and the clutch 5a is connected again after the rotational speed Ne of the engine is brought into agreement with the synchronizing rotational speed Ns relative to the clutch 5a. 
That is, the controller 10 includes clutch disconnection means for disconnecting the clutch 5a at the time of changing the speed of the engine 1, synchronizing rotational speed-operating means for operating a synchronizing rotational speed Ns of the engine rotational speed Ne that comes into agreement with the output rotational speed of the clutch 5a (input rotational speed of the transmission 5b), and clutch re-connection means for connecting the clutch 5a again at a moment when the engine rotational speed Ne comes into agreement with the synchronizing rotational speed Ns.
In a conventional device for controlling the engine equipped with the synchronous mesh-type automatic transmission disclosed in Japanese Unexamined Patent Publication (Kokai) No. 9921/1990, for example, the throttle opening degree xcex8 is so controlled that the engine rotational speed Ne maintains a synchronizing rotational speed Ns relative to the clutch 5a during the period from when the clutch is disconnected for changing the speed until when the clutch is connected again.
FIGS. 6 and 7 are timing charts illustrating the operation for changing the speed using the conventional device disclosed in the above publication, wherein FIG. 6 illustrates the operation during the acceleration (while being shifted up) and FIG. 7 illustrates the operation during the deceleration (while being shifted down).
Referring to FIG. 6, when the driver operates a gear shift lever, the controller 10 detects the up-shifting state during the acceleration based upon the engine rotational speed Ne and the shift position GS, and disconnects the clutch 5a. 
In order to bring the engine rotational speed Ne into agreement with the synchronizing rotational speed Ns (see a dotted line in FIG. 6) relative to the clutch 5a, the controller 10 so actuates the throttle actuator 3 that the throttle opening degree xcex8 is brought to the fully closed side thereby to lower the engine rotational speed Ne.
The synchronizing rotational speed Ns can be inversely operated by the synchronizing rotational speed operating means in the controller 10 by being replaced by the engine rotational speed Ne based on, for example, the vehicle speed Vr and the shift position GS.
The throttle opening degree xcex8 while the clutch 5a is being disconnected is set to a target opening degree for equalizing the engine rotational speed Ne to the synchronizing rotational speed Ns.
As shown in FIG. 6, therefore, the engine rotational speed Ne converges to the synchronizing rotational speed Ns with the lapse of time.
Thereafter, at a moment when it is detected that the engine rotational speed Ne is brought into agreement with the synchronizing rotational speed Ns, the controller 10 connects the clutch 5a again and gradually increases the throttle opening degree xcex8.
This executes the acceleration control operation depending upon the accelerator opening degree xcex1 requested by the driver, reduces the shock of connection of the clutch at the time of changing the speed, and prevents deterioration in the drive feeling.
Referring to FIG. 7, when a down-shifting state is detected during the deceleration, the controller 10 disconnects the clutch 5a, so actuates the throttle actuator 3 that the throttle opening degree xcex8 is brought to the fully opened side to increase the engine rotational speed Ne, so that the engine rotational speed Ne is brought into agreement with the synchronizing rotational speed Ns (see a dotted line in FIG. 7).
Thereafter, at a moment when it is detected that the engine rotational speed Ne is brought into agreement with the synchronizing rotational speed Ns, the controller 10 connects the clutch 5a again and gradually decreases the throttle opening degree xcex8.
This executes the deceleration control operation depending upon the accelerator opening degree xcex1 requested by the driver, reduces the shock of connection of the clutch at the time of changing the speed, and prevents deterioration in the drive feeling.
In the device for controlling the engine equipped with the synchronous mesh-type automatic transmission as described above, the throttle opening degree xcex8 is controlled and the engine rotational speed Ne is brought into synchronism with the input rotational speed (synchronizing rotational speed Ns) of the transmission 5b in order to reduce the shock at the time of changing the speed.
However, it has been known that a relation between the throttle opening degree xcex8 and the synchronizing rotational speed Ns varies depending upon the individual engines 1 and the warmed-up state, and it is very difficult to correctly set a target value of the throttle opening degree xcex8 when the clutch 5a is being disconnected.
Further, when the throttle opening degree xcex8, while the clutch 5a is being disconnected, is maintained at a target opening degree corresponding to a target engine rotational speed Ne (=Ns) as shown in FIGS. 6 and 7, the follow-up performance of the engine rotational speed Ne becomes dull, and an extended period of time is required before the engine rotational speed Ne is brought into agreement with the synchronizing rotational speed Ns.
As shown in FIGS. 6 and 7, further, when the clutch 5a is connected in a stable state where the engine rotational speed Ne is in perfect agreement with the synchronizing rotational speed Ns, the feeling for changing the speed is suppressed, too; i.e., the feeling for the driver who requests acceleration or deceleration is rather impaired.
In the conventional device for controlling the engine equipped with the synchronous mesh-type automatic transmission as described above, the relationship between the throttle opening degree xcex8 and the synchronizing rotational speed Ns varies depending upon the operation conditions. Therefore, it is difficult to correctly set the throttle opening degree xcex8 at the time of changing the speed to a target opening degree corresponding to the synchronizing rotational speed Ns, and the engine rotational speed Ne cannot be brought into correct agreement with the synchronizing rotational speed Ns.
Further, since the throttle opening degree xcex8 during the change of the speed (while the clutch 5a is disconnected) is maintained at a target opening degree corresponding to a target value (=Ns) of the engine rotational speed Ne, an extended period of time is required before the engine rotational speed Ne is brought into agreement with the synchronizing rotational speed Ns.
Besides, since the clutch 5a is connected again in a stable state in which the engine rotational speed Ne is in perfect agreement with the synchronizing rotational speed Ns, the feeling for the driver who requests acceleration or deceleration is impaired.
The present invention was accomplished in order to solve the above-mentioned problem, and its object is to provide a device for controlling the engine equipped with a synchronous mesh-type automatic transmission which features improved response at the time of changing the speed and improved drive feeling.
A device for controlling an engine equipped with a synchronous mesh-type automatic transmission of the present invention comprises:
various sensors for detecting the operation conditions of an engine inclusive of an engine rotational speed;
a throttle actuator for adjusting the throttle opening degree for setting the amount of the air taken in by the engine;
an automatic transmission including a synchronous mesh-type clutch and a transmission, connected to the output side of the engine; and
a controller for controlling the throttle actuator and the automatic transmission based upon the operation conditions;
wherein the controller includes:
clutch disconnection means for disconnecting the clutch at the time of changing the speed of the engine;
synchronizing rotational speed-operating means for operating the synchronizing rotational speed of the engine rotational speed so as to be brought into synchronism with the output rotational speed of the clutch while the clutch is being disconnected;
throttle opening degree-fixing means for fixing the throttle opening degree to a first predetermined opening degree, so that the engine rotational speed quickly converges to the synchronizing rotational speed while the clutch is being disconnected;
throttle opening degree-returning means for gradually returning the throttle opening degree from said first predetermined opening degree toward an opening degree corresponding to said synchronizing rotational speed at a moment when a difference in the rotational speed between the engine rotational speed and the synchronizing rotational speed has converged to lie within a first predetermined range; and
clutch re-connection means for connecting the clutch again at a moment when the direction of change in the engine rotational speed is inverted.
In the device for controlling the engine equipped with the synchronous mesh-type automatic transmission of the present invention, the clutch re-connection means connects the clutch again at a moment when the difference in the rotational speed has converged to lie within a second predetermined range after the direction of change in the engine rotational speed is inverted.
In the device for controlling the engine equipped with the synchronous mesh-type automatic transmission of the present invention, the throttle opening degree-returning means sets the throttle opening degree to the second predetermined opening degree between a first predetermined opening degree and an opening degree corresponding to the synchronizing rotational speed at a moment when the difference in the rotational speed has converged to lie within the first predetermined range, and gradually returns the throttle opening degree from the second predetermined opening degree toward the opening degree corresponding to the synchronizing rotational speed.
In the device for controlling the engine equipped with the synchronous mesh-type automatic transmission of the present invention, when the engine is under an accelerating condition and the automatic transmission is in an up-shifting state, the throttle opening degree-fixing means sets the first predetermined opening degree to be smaller than the throttle opening degree that maintains the synchronizing rotational speed, and the throttle opening degree-returning means gradually increases the throttle opening degree from a moment when the difference in the rotational speed has converged to lie within the first predetermined range.
In the device for controlling the engine equipped with the synchronous mesh-type automatic transmission of the present invention, the throttle opening degree-fixing means sets the first predetermined opening degree to the fully closed position.
In the device for controlling the engine equipped with the synchronous mesh-type automatic transmission of the present invention, when the engine is under a decelerating condition and the automatic transmission is in a down-shifting state, the throttle opening degree-fixing means sets the first predetermined opening degree to be larger than the throttle opening degree that maintains the synchronizing rotational speed, and the throttle opening degree-returning means gradually decreases the throttle opening degree from a moment when the difference in the rotational speed has converged to lie within the first predetermined range.
In the device for controlling the engine equipped with the synchronous mesh-type automatic transmission of the present invention, the throttle opening degree-fixing means sets the first predetermined opening degree to the fully opened position.